Printers are subject to occasional image quality (IQ) problems. The possible causes of the problems are dependent on the printing technology (e.g., inkjet, laser, thermal, dye-sublimation) involved. In some cases, the cause of the problem can be readily discerned from an image. For example, it may be apparent from an image that the source for the color yellow has been depleted. In other cases, the cause of the image-quality problem may not be readily apparent.
To facilitate diagnoses of image-quality problems, many printers provide for trouble-shooting procedures to help identify the problem source. One common approach is to make a test of print diagnostic patterns that can be examined to isolate potential sources of problems. For example, for a multi-nozzle inkjet printer, a pattern can consist of a series of lines, each to be formed using ink from a respective nozzle. A missing line can be used to identify a problematic (e.g., clogged) nozzle.
However, the test-print approach suffers from a number of limitations. In the first place, many image-quality problems are intermittent. Problems appearing in a user image may not be replicated in a test image, and vice-versa. Also, where a problem may have more than one source, some test procedures can yield confusing results, which can in turn lead to wasteful misguided attempts to solve the problem. What is needed is a more effective approach to identifying the source of an image-quality problem.
Herein, related art is described to facilitate understanding of the invention. Related art labeled “prior art” is admitted prior art; related art not labeled “prior art” is not admitted prior art.